package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

/**
 * 基于redis的分布式锁
 */
public class SimpleRedisLock implements ILock{
    private StringRedisTemplate stringRedisTemplate;
    //定义锁名字
    private String name;
    private static final String KEY_PREFIX = "lock:";
    public SimpleRedisLock(String name,StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }

    /**
     * 获取锁
     * @param timeoutSec 锁持有的超时时间，过期后自动释放
     * @return
     */
    //通过uuid获取唯一标识
    private static final String ID_PREFIX= UUID.randomUUID().toString(true) +"-";
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    //脚本初始化
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }
    @Override
    public boolean tryLock(long timeoutSec) {
        //获取线程id,以线程id当值，获取线程标识-uuid

        String threadId = ID_PREFIX+Thread.currentThread().getId();
        //获取锁
        Boolean success = stringRedisTemplate.opsForValue()
                .setIfAbsent(KEY_PREFIX + name, threadId, timeoutSec, TimeUnit.SECONDS);
        //如果是null也返回true，防止自动拆箱导致空指针
        return success.TRUE.equals(success);
    }

    /**
     * 释放锁
     */
//    @Override
//    public void unlock() {
//        //获取线程标识
//        String threadId = ID_PREFIX+Thread.currentThread().getId();
//        //获取锁中的标识
//        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
//        //判断标识是否一致
//        if(threadId.equals(id)){
//
//            //释放锁
//            stringRedisTemplate.delete(KEY_PREFIX + name);
//        }
////        //释放锁
////     stringRedisTemplate.delete(KEY_PREFIX + name);
//    }

    /**
     * 调用lua脚本释放锁
     */
    @Override
    public void unlock() {
    //调用lua脚本
        stringRedisTemplate.execute(UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + name),
                ID_PREFIX+Thread.currentThread().getId());

    }
}
